On radiation-induced fluidization (quasi-melting) of silicate glasses

Abstract

AbstractThe effect of intensive electron radiation on viscous flow in silicate glasses is analysed and shown that it can result in a many orders of magnitude decrease of viscosity and stepwise decrease of activation energy of flow. Fluidisation or quasi-melting of glasses on intensive electron irradiation is caused by bond breaking via the radiation-chemical reaction ≡Si-O-Si≡ + e− Si-O + Si + (e−)′ which weakens the silicate glass network and leads tofive-fold coordination of oxygens around the silicon. An explicit equation of viscosity wasobtained for irradiated glasses as well as an equation for glass transition temperature. Theassessments of temperature increase by electron radiation show that radiation-inducedfluidisation of glasses can occur at minimal thermal effects. Radiation-induced fluidisation ofglasses can result in nanoscale patterning effects caused by surface tension forces. Changes inthe viscous flow behaviour are also important in conditions of long-term irradiation for glassesused in nuclear installations as well as for nuclear waste glasses.